In a comment @Sam Blake asked a follow up question about an integer to factor:
The question is this 2nd semiprime actually trivial to factor into primes?
This semiprime is not weak because it does not give up its' special form very easily.
It is weak for an adversary with nation state capability because it is only 701 bits.
A 2048 bit or higher modulus with equal bitlength p and q are recommended.
Also it doesn't appear to have weakness using Fermat's, p-1, it's ratio is not near a small
fraction, ECM is not helpful.
This integer does not appear to match a special form that is easy to factor. Even though
once the special form is recognized the number can be factored with much less effort,
detecting which special form can be very time consuming as there are many forms.
What hints are you willing to give? That this is a semiprime? That the factors
are of unequal length? That the factors are polynomials with terms:
a0 x 2^(k0) + a1 x 2^(k1) + a2 x 2^(k2)...